The present invention relates to a printing head for use in wire impact dot printers, and more particularly to a printing head suitable for wire impact dot printers characterized by heat radiating means and nose frame positioning and fixing means.
Conventionally, a printing head for use in wire impact dot printers includes a heat radiating member with a fin, inserted around a core block which dissipates heat generated by a coil into the air.
This structure, however, has disadvantages when high density characters are printed continuously at high speed. The heat generated by the coil exceeds the amount of heat dissipated by the heat radiating member so that continuous printing is precluded. In order to overcome this problem, Japanese Laid-Open Utility Model Publication No. 63-68436, which corresponds to U.S. Pat. No. 4,795,283, proposes a printing head which releases the heat generated by the coil through the printer carriage or guide shaft.
A nose base as a heat radiating member is mounted directly to the carriage to conduct heat to the carriage. In addition, both the nose frame and the core block are positioned so that both contact the reference surface of the nose base, thus increasing the mountability and the heat radiating effect due to heat conduction. This structure has a disadvantage in that an unavoidable gap is formed between the carriage and core block. This gap does not provide sufficient heat conduction, and in addition, it cannot absorb an impact force which is exerted against the nose frame during printing. The impact force can detrimentally affect the nose frame and other components of the printer.